On-board detection of pressure regulator malfunction

Abstract

The present invention is directed to an on-board diagnostic system for detecting a defective fuel line pressure regulator in an internal combustion engine during engine operation. Pressure sensor means are provided for sensing fuel pressure in the fuel supply line and for generating corresponding pressure signals. Signal processing means receive and process the pressure signals from the pressure sensor means. An output signal is generated by the signal processing means in the event pressure signals are determined to indicate a malfunctioning pressure regulator. Such output signal can be stored, used to alert an engine operator to an impaired regulator and/or provided to a fuel injector control means for adjusting the duration of injector actuation to better achieve a desired fuel flow quantity per individual actuation.

We claim: 
     
       1. An internal combustion engine having an on-board diagnostic system for detecting a malfunctioning fuel line pressure regulator during engine operation, comprising: fuel supply means for supply liquid fuel under pressure to combustion cylinders of the engine, comprising the fuel line pressure regulator operatively connected to a fuel supply line;   pressure sensor means for generating pressure signals corresponding to transient fuel pressure waves in the fuel rail, comprising a pressure transducer mounted to the fuel supply line with a pressure responsive diaphragm exposed to fuel in the fuel supply line and a signal conditioner to generate the pressure signal as a continuous analog voltage output signal varying with pressure sensed in the fuel supply line;   signal processing means comprising a waveform analyzer having means for Fast Fourier Transform analysis of the pressure signals, operatively connected to the pressure means for receiving and processing pressure signals from the pressure sensor means in a frequency range of 50 to 1,000 Hz, and for generating an output signal in response to pressure signals corresponding to transient fuel pressure waves indicative of malfunction of the pressure regulator; and   utilization means operatively connected to the signal processing means for receiving the output signal and manifesting its presence.   
     
     
       2. The internal combustion engine of claim 1 wherein the signal processing means is for determining a magnitude value of the pressure signals over a first time period during engine operation and for comparing the magnitude value to a stored value, and wherein the output signal is generated when the difference between the magnitude value and the stored value exceeds a preselected amount.